When a pigment is used as a colorant, an ink composition is prepared by mixing the concentrated pigment dispersion which contains pigment, water, dispersant and the like with water, resin, a water-soluble organic medium, and other ingredients.
U.S. Pat. No. 6,818,053 discloses a production process for producing a pigment dispersion comprising the steps of (a) providing a mixture consisting essentially of a pigment, a dispersant, a polysiloxane surfactant and/or an alkanediol, a polyhydric alcohol and water; and (b) dispersing the mixture to produce the pigment dispersion. The patent also claims an ink composition prepared from the above pigment dispersion.
In pigmented ink compositions, the pigment dispersion is generally stabilized by a dispersant which serves to prevent the pigment particles from agglomerating and settling out of the carrier. U.S. Pat. No. 5,085,698 discloses an ink composition comprising pigment, aqueous medium, and an acrylic/acrylate block copolymer as a stabilizing agent. U.S. Pat. No. 5,589,522 employs a graft polymer comprising a hydrophilic polyacrylic acid backbone and hydrophobic segment side chains in an aqueous ink composition. U.S. Pat. No. 4,597,794 discloses an aqueous ink dispersion for ink jet printers in which pigment is contained in a polymer having ionic hydrophilic segments and aromatic hydrophobic segments that adhere to the pigment surface.
U.S. Pat. No. 5,948,843 relates to a lithographic printing ink containing a dispersing agent of a reaction product of a styrene/maleic anhydride (SMA) copolymer and an alcohol as a pigment dispersant. U.S. Pat. No. 5,302,197 employs hydroxyl-terminated branched polymer off a short carbon chain in an ink jet ink.
While prior pigmented ink compositions showed acceptable stability for the pigment dispersion, improved pigment ink dispersion is still needed to further lower the ink viscosity, impart better print density, increase pigment loading, and lower degree of shear thinning after aging. It is therefore an object of the present invention to provide an improved pigmented ink composition.
Additionally, pigments may be incorporated into pigmented coating compositions by mixing a pigment dispersion and a grind resin. The coating composition may further include additives such as crosslinkers, solvents, additional polymer resins, flow and appearance control agents, fillers, and the like.
In general, the coating compositions may be used to provide a protective layer, which is ascetically pleasing, on metals, alloys, composites, plastics, concrete, cast iron, wood, ceramic, paper, film, foil, vinyl, textile, glass, leather, and the like materials. In particular, the coating compositions disclosed herein may be applied to the surfaces of automobiles, automobile parts, decks, fences, homes, and the like surfaces.
U.S. Pat. No. 7,005,473 discloses a pigment dispersion used in solventborne coating compositions. The patent further discloses the use of a polymeric pigment disperant as the grind resin to incorporate the pigment into the pigment dispersion for solventborne coating compositions. U.S. Pat. No. 7,005,473 is hereby incorporated by reference in full, to the extent that its disclosure does not contradict the instant disclosure.
While prior pigmented coating compositions showed acceptable stability for the pigment dispersion, improved pigment dispersion is still needed to further lower the coating viscosity, impart better print density, increase pigment loading, and lower degree of shear thinning after aging. It is therefore an object of the present invention to provide an improved pigmented coating composition.
The present invention thus defines a novel and inventive class of dispersant materials useful in formulating inks, coatings, and the like, including ink formulations and pigmented coating compositions comprising such dispersant materials as defined herein.